An Uninterruptible Power Supply (UPS) may be installed in a data center to provide back-up power in case of a mains power failure. The UPS is typically configured to provide sufficient power to allow the data center equipment to continue running while a generator is started. Lead-acid batteries are generally used to provide back-up power to the data center equipment. Lead-acid batteries are cheaper than other energy storage systems, and in UPS applications, lead-acid batteries are typically sized to provide enough power to allow the data center equipment to continue to run for a sufficient period of time to start a generator.